Piezoelectric actuators are used in a large variety of fields where accurate positioning is required. The applicant's own prior patent publications provide examples of prior art configurations. In particular, the following prior art documents are acknowledged and enclosed by reference: U.S. Pat. Nos. 7,026,745, 7,095,915, 7,106,925, 7,231,126, 7,389,016, 7,876,981, 7,522,789, and 8,358,929.
From an electrical viewpoint the actuators of the kind employed in these prior art switches are mainly a capacitive load and are controlled by applying a voltage signal to the actuator by means of a driver circuit. Several applications, in particular in the field of optical switches require large arrays of piezoelectric actuators of which the controlling voltage signal needs to be switched within a certain time frame.
When several driver circuits have the same electrical supply, by sharing either or both the ground and positive supply line, the electrical cross-talk between driver voltages can become a significant issue. Especially the dynamic electrical cross-talk voltage, generated by switching the voltage signal at a certain driver, is problematic since compensation by means of a position feedback loop is very difficult to achieve (in the case of piezoelectric actuators) due primarily to limitations on the position feedback loop bandwidth. This issue becomes even more pronounced when integrating several drivers onto a single chip due to the nature of on-chip ground and supply lines which typically have a larger impedance than traces on a printed circuit board (PCB).
The cause of the cross-talk is the impedance of the supply/ground feed lines or in some cases the output impedance of the voltage supply used to power the driver circuit. In order to reduce the dynamic electrical cross-talk between channel voltages a simple method might be to lower the impedance of the supply feeds and to lower the output impedance of the voltage supply or/and add more decoupling to the voltage supply. However close placement of drivers on a PCB or integration of several drivers onto a chip results in a lower limit to the impedance that can be achieved.
The above mentioned issue of inter-driver cross-talk leads to a need for a system-level solution(s) to reduce the electrical cross-talk between channels.